The present invention relates to a system for measuring the liquid volume or quantity in one or more tanks. The overall system is microcomputer-controlled and provides a readout of liquid or fuel volume or quantity.
A basic sensor for measuring fuel volume or quantity continues to be the capacitance sensor which has been accepted in the aircraft industry for many years as a rugged, reliable device. In the present invention, significant improvement in sensor gaging accuracy is obtained by use of a microcomputer to provide tank shape, tank or aircraft attitude, and similar characterization which was formerly only approximated by means of physically characterized (shaped) fuel gage probes.
In this manner, the present invention provides a number of advantages over conventional fuel gaging systems. These include the need for a fewer number of fuel gage probes in each tank, simplified probe construction by elimination of physical characterization, improved system accuracy by characterizing for tank geometry and tank or airplane attitude in the microcomputer, reduced system weight by decreasing the number of fuel gage probes, and simplified installation for the aircraft manufacturer by requiring fewer tank units. In addition, as further explained below, indicators are precalibrated, thus reducing installation costs and replacement time, and common apparatus may be used for all primary and repeater indicators, thereby reducing spares costs and simplifying logistics. Compatibility with solid state indicator design also provides potential for improved system accuracy. Further, compatibility with high frequency fuel gage probe excitation provides means for reduced contamination and water problems. Lastly, computer characterization provides a more flexible design which can accommodate fuel tank changes with minor hardware impacts.